The transducing properties of slowly adapting stretch receptors of the trachea will be further investigated considering their capability to respond to longitudinally applied forces (in addition to the previously tested transversally applied forces) and analyzing the mechanical basis of their adaptation, i.e., the stress-relaxation of the tracheal posterior wall in which they lie. The possibility of inducing a selective blockade of either the slowly or the rapidly adapting tracheal receptors using topically applied local anesthetics will be studied as the basis for separating the reflex influences originating from each type of receptor. The possibility to stimulate the rapidly adapting tracheal receptors in isolation from the slowly adapting stretch receptors using their different circumferential location will provide a more direct approach for evaluating their role in the control of breathing.